Characteristics of fine particle explosive growth events in Beijing, China: Seasonal variation, chemical evolution pattern and formation mechanism

Zirui Liu; Bo Hu; Dongsheng Ji; Mengtian Cheng; Wenkang Gao; Shuzhen Shi; Yuzhu Xie; Shuanghong Yang; Meng Gao; Hongbo Fu; Jianming Chen; Yuesi Wang

doi:10.1016/j.scitotenv.2019.06.068

Characteristics of fine particle explosive growth events in Beijing, China: Seasonal variation, chemical evolution pattern and formation mechanism

Sci Total Environ. 2019 Oct 15:687:1073-1086. doi: 10.1016/j.scitotenv.2019.06.068. Epub 2019 Jun 6.

Authors

Zirui Liu¹, Bo Hu¹, Dongsheng Ji¹, Mengtian Cheng¹, Wenkang Gao¹, Shuzhen Shi², Yuzhu Xie¹, Shuanghong Yang², Meng Gao³, Hongbo Fu⁴, Jianming Chen⁵, Yuesi Wang⁶

Affiliations

¹ State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100191, China.
² State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100191, China; Department of Environmental Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
³ John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
⁴ Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China.
⁵ Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China. Electronic address: jmchen@fudan.edu.cn.
⁶ State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100191, China; Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: wys@mail.iap.ac.cn.

PMID: 31412445
DOI: 10.1016/j.scitotenv.2019.06.068

Abstract

Fine particle explosive growth (FPEG) events are frequently observed in heavy haze episodes in Beijing, the characteristics and formation mechanism of which remain not fully understood. In this study, a five year (2013-2017) online observation was conducted in Beijing and the chemical evolution pattern of FPEG events was analyzed to understand its formation mechanism. A total of 132 FPEG events were identified, and steadily decreased from 39 events in 2013 to 19 events in 2017. More than 70% of the FPEG events occurred in winter and autumn, which coincides with adverse weather conditions and enhanced primary emissions. Organic matter (OM) was the dominated components (~30%) in PM_2.5, but it only accounted for 10% of total FPEG events as a driven factor, because its contribution usually decreased when the FPEG events developed. In contrast, the secondary inorganic species were the dominated driven factors, and sulfate-driven events accounted >50%. During the period of 2013-2017, the contribution from regional sources decreased significantly mainly due to the reduction of emissions from regional sources, while the contribution from local sources remained largely unchanged, indicating that the local secondary transformation played a leading role in promoting the FPEG events. The low nitrogen oxidation rates (NOR, 0.12 ± 0.07) and the weak increase trend of NOR with elevated RH were observed, indicating the formation of which might be promoted by the homogenous reaction between HNO₃ and NH₃. In contrast, a significant increase in sulfur oxidation rate (SOR, 0.50 ± 0.19) was observed when RH > 50%, suggesting enhanced heterogeneous oxidation of SO₂ in FPEG events. In addition, our analysis suggest the S (IV) heterogeneous oxidation rates in FPEG events depend mainly on the aerosol liquid water content (ALWC) in addition to the aerosol acidity. This study provides observational evidence for understanding the formation mechanism of FPEG events in Beijing.

Keywords: Chemical evolution pattern; FPEG events; Formation mechanism; Local/regional contribution.